Checking voltage at Fuel Pump

[txleadfoot]

How do I test the electrical connector at the fuel pump (not the level sender) with a multimeter? I can't get a reading on any of my running 318s with the ignition on (not running). Nada. Even tried using the chassis as a ground. Also tried another working multimeter. This is on 3 cars, two of which are running. I'm stumped!

Thanks,
Shaun

[NC325iC]

you have to have someone crank it over or jumper the connection, it doesnt turn on but for a second until you start the car

[jlevie]

The pump only runs when the DME sees timing reference data from a rotating engine. So as NC325iC said, you'll have to check for voltage while cranking the engine over.

I suspect that you are doing this check on the car that isn't running as a part of the diagnosis. The definitive test for the fuel system is to connect a gauge at the inlet of the fuel rail and try to start the car. If the pressure doesn't reach close to 4bar after a turn or two of the engine, the pump isn't working. That can be as a result of:

1) Bad fuel pump or main relay.
2) Bad fuel pump.
3) Bad FPR
4) Plugged filter or collapsed line
5) Bad crank position sensor
6) bad DME or no power to the DME
7) No fuel in the tank.

If the engine has spark, the DME and crank position sensor aren't likely to be involved.